In the process of operating the no-load transformer, there will be an unavoidable physical phenomenon, that is, cut-off. The problem of operating overvoltage due to the cut-off of the circuit breaker can be prevented by taking the following measures:

1. Improve the iron core

Improving the iron core has a certain effect on reducing the no-load current. Because the magnetizing current and the iron loss current together form the no-load current, and the magnetizing current will generate magnetic flux, and the iron core loss will cause the iron loss current, so the iron core of the transformer is the key factor to reduce the no-load current. Further improving the core structure and improving the quality of the iron core are two basic measures. Cold-rolled grains can be used instead of silicon steel sheets, because the magnetic permeability system of cold-rolled grains is relatively high. When the transformer is overhauled, the iron core must be inspected and inspected strictly according to the relevant quality standards.

2. Winding adopts tangled type

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The 220kV transformer is a core transformer. If the winding method is tangled winding, the parasitic capacitance of the transformer will increase. The entangled winding is to insert another turn of the winding directly between the electrically adjacent turns, so that the longitudinal capacitance of the winding increases, and the actual potential difference between the adjacent turns will further increase, so that in the presence of In the event of an overvoltage phenomenon, the initial voltage can be evenly distributed among the turns.

3. Use a switch with a parallel resistor

At the moment of current cut-off, the magnetic field energy in the inductor will be converted into electrical energy to charge the capacitor. At this time, if the switch is connected in parallel with the resistor, the magnetic field energy in the inductor can be released. After the switch with parallel resistance is closed before the current cut-off, the switch parallel resistance is short-circuited. After the current cut-off, the switch traps the R84Th N resistor to form a current, so that the magnetic field energy in the inductor will be consumed.